Pumps of the general type described herein are well known. Such pumps may have one, two, or more pumping chambers and generally have a piston (e.g., a wobble piston, an articulated head piston or a diaphragm piston) reciprocating in the pumping chamber that is driven by a motor. If there are two pumping chambers with parallel axes, the motor is typically between two housings that define the crankcases of the pump and join the motor to the pumping chambers, with the motor shaft axis perpendicular to the pumping chamber axis. In a useful form, a monolithic head spans the two pumping chambers, for example as in U.S. Pat. No. 6,056,521, which is hereby incorporated by reference.
The ends of the housings opposite from the motor have typically been closed off at least partially with a fan guard that lets air through or a cover of some kind that required additional fasteners to hold the cover on. This required additional assembly and additional parts. In addition, the valve plate, which, if separate from the head, is typically provided right below the head, typically had flanges through which the tie rods would extend that hold the head on the housing, with the cylinder and possibly other parts in between. These flanges could create problems in assembly by requiring orientation of the valve plate to register with the bolt holes of the head and also in some cases could result in leakage, for example if the head flange would interfere with the flange of the valve plate. In other structures, the valve plate required separate fasteners apart from the fasteners that held the head on, to hold the valve plate on.
In addition, each piston is assembled to the drive shaft and formerly this was typically done with flats on the motor shaft, the flat on one end being 180° out of phase with the flat on the other end so that the pistons were out of phase also. The set screw against a flat introduces errors in assembly in that they do not necessarily result in the pistons being 180° out of phase. For single-ended pumps, the phase is not an issue, but for double-ended pumps, a reliable method is needed to assure that the pistons are 180° out of phase, while not making assembly difficult.
In addition, these pumps can find many different applications. For that reason, it is useful to have different port arrangements possible for these pump configurations.
Pumps of this type also can be provided with different removable or separate port arrangements. For this purpose, it would be useful to have an easy way to add a port or a plug to the pump.
Also as is well known, pumps of this type can produce significant noise and vibration. Isolation is a major design goal in most applications. A solution is needed in this area as well which results in good performance at low cost and easy assembly.